EXTSW 21 mm ID x 28.3 mm OD x 6.35 mm Thick 316 Stainless Washer

First, the dimensional precision and finish of these washers (spacers) is outstanding. I am using these with new multifunction workbenches with grids of 20 mm holes that have tops that are approximately 0.5 inch thick. Most of the 20 mm diameter bench dogs I have extend 16 to 18 mm below the upper surface of the tops making it impossible to lock the bench dogs vertically with through bolts. Using these spacers under the bench top around the protruding bench dogs allows me to lock in the dogs with a fender washer and through bolt. Only downside is these beautifully finished spacers are hidden from view!